High-performance polyester composite material as well as preparation method and application thereof

Abstract

The invention relates to the technical field of engineering plastics, in particular to a high-performance polyester composite material as well as a preparation method and application thereof. The high-performance polyester composite material is prepared from 35 to 60 parts of polybutylene terephthalate, 10 to 20 parts of brominated flame retardant, 2 to 6 parts of flame-retardant synergist, 1 to 5 parts of flexibilizer, 10 to 40 parts of glass fiber, 0.1 to 1 part of antioxidant, 0.1 to 2 parts of lubricant and 0.1 to 0.6 part of flow promoter, the intrinsic viscosity of the polybutylene terephthalate is 0.75 to 1.0 dl / g; the glass fibers comprise alkali-free short glass fibers and ground glass fibers; the flow promoter is a hyperbranched polymer containing hydroxyl. The high-performance polyester composite material provided by the invention has good comprehensive performance of high fluidity, low floating fiber, low warping and high strength, can be applied to the fields of automobiles and electronic and electric appliances, and particularly has good application prospects in thin-walled products with complex structures.

Description

Technical Field

[0001] This invention relates to the field of engineering plastics technology, and in particular to a high-performance polyester composite material, its preparation method, and its application. Background Technology

[0002] Thermoplastic polyester engineering plastics are widely used in high-end manufacturing fields such as automobiles and electronics due to their excellent mechanical strength, heat resistance, electrical insulation properties, and chemical corrosion resistance. Among them, polybutylene terephthalate (PBT) is produced by esterification of terephthalic acid and 1,4-butanediol under high temperature and atmospheric pressure catalysis and high temperature vacuum polycondensation in the presence of tetrabutyl titanate. It possesses good melt flowability, excellent electrical properties, and chemical stability. However, PBT resin itself is notch sensitive, and its room temperature impact resistance is generally poor, making it difficult to meet the toughness requirements of complex parts. Therefore, blending modification is necessary to improve its performance.

[0003] Existing technologies generally use a variety of additives such as glass fiber, flame retardant, and toughening agent to blend and granulate with PBT to obtain comprehensive properties such as high strength, flame retardancy, and heat resistance. However, the introduction of the above-mentioned additives brings about the following three prominent problems: (1) Significantly reduced fluidity: Due to the flow obstruction of glass fiber orientation and the frictional thickening effect of flame retardant particles, the melt viscosity of the glass fiber reinforced flame retardant system increases significantly, the injection pressure increases, and the mold filling is difficult, making it difficult to meet the molding requirements of thin-walled and long-process parts; (2) Surface floating fiber and appearance defects: Glass fiber is easy to accumulate on the surface of the product, forming appearance defects such as "floating fiber" and "hemp", reducing the aesthetics of the product and the adhesion of subsequent coatings; (3) Increased warping deformation: The anisotropy of glass fiber leads to differences in molding shrinkage, increasing the warping of the parts and reducing dimensional stability, which brings difficulties to high-precision assembly.

[0004] To address the above issues, the industry has attempted various modification routes: (1) Introducing amorphous polymer blends: For example, the invention patent with publication number CN112852119A uses low-viscosity polycarbonate (PC) and PBT to reduce shrinkage differences and improve warpage by utilizing the amorphous properties of PC. However, PC has a high content of benzene rings in its main chain and its melt viscosity is much higher than that of PBT, which leads to further deterioration of the fluidity of the alloy system. Even with the addition of hyperbranched polyester to increase flow, a higher addition amount is required to be effective. Excessive hyperbranched polyester will reduce the processing window, making it easier for thin-walled and complex parts to have short shots and scorch marks. In addition, the addition of PC prolongs the mold cooling time, which is not conducive to efficient and energy-saving production. (2) Filling with shaped glass fiber or flat glass fiber: For example, the invention patents with publication numbers CN117304664A and CN118562261A replace traditional cylindrical glass fiber with shaped glass fiber or flat ground glass fiber with non-circular cross sections. They use their wide cross sections to reduce orientation differences, thereby alleviating warpage to a certain extent and slightly improving fluidity. However, the preparation process of irregular glass fiber is complicated and costly, and the reduction in melt viscosity is limited, so it cannot achieve ultra-high fluidity. (3) Low viscosity PBT matrix or lubricant: Although the use of low molecular weight, wide distribution PBT resin or high content lubricant system can reduce melt viscosity, the low molecular weight components are very easy to migrate to the surface of the product under high temperature injection molding conditions, resulting in appearance defects such as fogging and air marks, which affects the product qualification rate.

[0005] As applications in automotive electronics, precision connectors, and thin-walled relay housings evolve towards more complex structures, thinner walls, and multi-cavity, hot-runner molds, the traditional melt flow index (MFR) can no longer accurately reflect the material's flowability under dynamic injection molding conditions. The flow length ratio (the ratio of the flow end distance to the average wall thickness), because it simultaneously couples with actual process variables such as pressure, speed, and temperature, is widely recognized as an evaluation index closer to the true mold filling capacity. However, existing modified PBT systems struggle to achieve a balance between high flow length ratio and multiple properties such as low fiber float, low warpage, and high strength. Summary of the Invention

[0006] This invention provides a high-performance polyester composite material, its preparation method, and its application, in order to solve the aforementioned technical problems existing in the current modified PBT system.

[0007] According to a first aspect of the present invention, the present invention provides a high-performance polyester composite material, comprising the following components in parts by weight: 35-60 parts of polybutylene terephthalate 10-20 parts of brominated flame retardant 2-6 parts of flame retardant synergist 1-5 parts toughening agent 10-40 parts of fiberglass Antioxidant 0.1 to 1 part Lubricant 0.1~2 parts 0.1 to 0.6 parts of flow aid; The intrinsic viscosity of the polybutylene terephthalate is 0.75-1.0 dl / g; the glass fiber includes alkali-free short glass fiber and ground glass fiber; and the flow aid is a hyperbranched polymer containing hydroxyl groups.

[0008] In high-performance polyester composites, the higher the viscosity of PBT resin, the more tightly the chains of larger molecular weights are wound, resulting in poorer flowability compared to PBT with lower viscosity. Flowability is further reduced after modification with various flame retardants and glass fiber. Conversely, excessively low resin viscosity leads to a wider molecular weight distribution in low-viscosity PBT resin, significantly increasing the mass of small molecules. While this has little impact on flowability, small molecules migrate more easily to the surface of the product during use. Due to molding temperature and processes, these small molecules are more prone to scorching and carbonization, leading to application problems such as scorching, whitening, and frequent mold rubbing during actual molding and use. To balance flowability and appearance, the high-performance polyester composite material of this invention uses polybutylene terephthalate (PBT) with an intrinsic viscosity of 0.75-1.0 dl / g. Further, the intrinsic viscosity of the polybutylene terephthalate is 0.8-0.95 dl / g. Compared to linear polyol structures, this invention uses hydroxyl-containing hyperbranched polymers as flow aids. These polymers exhibit lower intermolecular forces and relatively shorter branched segments. Due to their highly branched nature and near-spherical three-dimensional structure, they act as "molecular beads" between polymer chains, significantly reducing chain entanglement and internal friction. When added to PBT matrix resin, the PBT polymer chains undergo partial transesterification with the hydroxyl-containing hyperbranched polymer, grafting branched structures onto the PBT segments, further reducing inter-segment entanglement and improving material flowability.

[0009] The addition of hydroxyl-containing hyperbranched polymers can significantly improve the initial flowability of PBT, further reducing the material viscosity during processing. However, if the heating time during processing is too long, it can actually increase the viscosity of the base resin. This is because a large amount of polyol additives, under prolonged heating, will generate a large number of cross-linked structures, leading to a sharp increase in molecular weight and molecular weight distribution. Through extensive research and experimentation, the inventors have found that when the addition ratio of hydroxyl-containing hyperbranched polymers is below 0.1%, it cannot significantly improve the material flowability. When the addition ratio is between 0.1% and 0.5%, the material flowability is significantly improved, manifested in a significant increase in the material flow length ratio. Extending the molding cycle, the material flow length ratio tends to increase. When the addition ratio exceeds 0.5% (e.g., 0.7%-1.0%), although the material flow length ratio increases somewhat, extending the molding cycle leads to a decreasing trend in the material flow length ratio.

[0010] The mass fraction of the hydroxyl-containing hyperbranched polymer used in this invention is 0.1-0.5%, specifically 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, or 0.5%.

[0011] The hydroxyl-containing hyperbranched polymers described in this invention are one or more of hydroxyl-containing hyperbranched polyol polyesters and hydroxyl-containing hyperbranched polyol polyamide esters.

[0012] The hydroxyl-containing hyperbranched polyester described in this invention can be selected from Perstorp's Boltorn H20, Boltorn H30, or Boltorn H40, with Boltorn H20 being preferred.

[0013] The hydroxyl-containing hyperbranched polyamide ester described in this invention can be selected from DSM Hybrane S 1200, Hybrane D 2800, or Hybrane P / S80 1200.

[0014] More preferably, the hydroxyl-containing hyperbranched polymer has a hydroxyl value of 300-550 mgKOH / g, and more preferably 450-550 mgKOH / g.

[0015] To achieve a product that balances low warpage and high flowability while maintaining high strength, this invention specifies the use of alkali-free short glass fibers and ground glass fibers in a ratio of (1-4):1. Optionally, alkali-free short glass fibers and ground glass fibers can be used in ratios of 1:1, 1.25:1, 1.5:1, 1.75:1, 2:1, 2.25:1, 2.5:1, 2.75:1, 3:1, 3.25:1, 3.5:1, 3.75:1, or 4:1. This invention utilizes a blend of alkali-free short glass fibers and ground glass fibers, which work synergistically to retain the reinforcing effect of alkali-free short glass fibers on the matrix material while leveraging the advantages of ground glass fibers in improving the flowability, appearance, and warpage resistance of the modified polyester material. If the proportion of ground glass fiber is too low, the anisotropy of alkali-free short glass fiber will have a greater impact during molding, resulting in more pronounced shrinkage and deformation of the product. The fluidity of the modified material will also be reduced due to the influence of the length of the alkali-free short glass fiber. This is especially true for thin-walled and structurally complex parts, where more obvious appearance defects and incomplete molding often appear at the ends of the product. If the proportion of ground glass fiber is too high, the mechanical strength of the modified high-performance polyester composite material will be lower.

[0016] Preferably, the alkali-free short glass fiber has a fiber diameter of 10-13 μm and a length of 3-5 mm. The ground glass fiber has a fiber diameter of 9-14 μm and a length of 80-200 μm, preferably 80-150 μm. More preferably, the bulk density of the ground glass fiber is 0.5-0.6 kg / L. If the bulk density of the ground glass fiber is too low, its flowability decreases and its dispersibility in polyester deteriorates, affecting the flowability and stability of various properties of the modified polyester material. If the bulk density of the ground glass fiber is too high, the glass fiber is ground into smaller pieces, which improves flowability but significantly reduces its reinforcing effect on the matrix material. Therefore, selecting a suitable bulk density for the ground glass fiber is crucial.

[0017] In this invention, the bulk density is measured according to the natural packing method of GB / T 16913.3-1997. Specifically, the measurement method is to let the ground glass fiber powder fall freely from a certain height to fill the measuring cylinder, and measure the mass of the ground glass fiber per unit volume in the loose state.

[0018] In this invention, the polybutylene terephthalate is 35 to 60 parts, for example, 35 parts, 38 parts, 40 parts, 43 parts, 45 parts, 48 ​​parts, 50 parts, 53 parts, 55 parts, 58 parts or 60 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0019] In this invention, the brominated flame retardant is 10 to 20 parts, for example, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19 or 20 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0020] In this invention, the flame retardant synergist is 2 to 6 parts, for example, 2 parts, 3 parts, 4 parts, 5 parts or 6 parts, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0021] In this invention, the toughening agent is 1 to 5 parts, for example, 1 part, 2 parts, 3 parts, 4 parts or 5 parts, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0022] In this invention, the glass fiber is 10 to 40 parts, for example, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, 35 parts or 40 parts, and specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0023] In this invention, the antioxidant is 0.1 to 1 part, for example, it can be 0.1 part, 0.2 part, 0.3 part, 0.4 part, 0.5 part, 0.6 part, 0.7 part, 0.8 part, 0.9 part or 1 part, as well as specific values ​​between the above-mentioned values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0024] In this invention, the lubricant is 0.1 to 2 parts, for example, it can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1 part, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, or 2 parts, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0025] In this invention, the flow aid is 0.1 to 0.6 parts, for example, it can be 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts, 0.55 parts or 0.6 parts, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0026] Furthermore, based on parts by weight, it includes the following components: 45-59 parts of polybutylene terephthalate 10-15 parts of brominated flame retardant 2-6 parts of flame retardant synergist 1-5 parts toughening agent 20-35 parts fiberglass Antioxidant 0.1 to 1 part Lubricant 0.1~2 parts 0.1 to 0.5 parts of flow aid.

[0027] Furthermore, the brominated flame retardant is one or more selected from brominated epoxy resin, brominated polystyrene, decabromodiphenyl ethane, pentabromobenzyl polyacrylate, brominated imine, brominated polycarbonate, and brominated triazine. By selecting a suitable type of brominated flame retardant, the flame retardant effect of high-performance polyester composite materials can be improved.

[0028] Preferably, the brominated flame retardant is one or more of brominated epoxy resin, brominated polystyrene, and pentabromobenzyl polyacrylate.

[0029] Furthermore, the flame retardant synergist is antimony trioxide or sodium antimonate. Antimony trioxide or sodium antimonate, as flame retardant synergists, can produce a synergistic effect with brominated flame retardants, significantly improving flame retardant efficiency.

[0030] Furthermore, the antioxidant is one or more of hindered phenolic, phosphite, and thioester antioxidants. By selecting appropriate types of antioxidants, the oxidative degradation process of polymers can be effectively inhibited or delayed, thereby helping to maintain the molecular weight stability of the material during processing, preventing yellowing, and ensuring that the final product maintains its original mechanical properties, appearance, and service life during long-term use.

[0031] Furthermore, the toughening agent is one or more selected from ethylene-methyl acrylate-glycidyl methacrylate, ethylene-butyl acrylate-glycidyl methacrylate, ethylene-butyl acrylate, and ethylene-vinyl acetate copolymer. By selecting a suitable type of toughening agent, the impact toughness and crack resistance of the material can be effectively improved. These toughening agents, as elastomer particles dispersed in the polymer matrix, can absorb energy and prevent crack propagation upon impact, thereby improving the brittleness of the material and making it more reliable and durable in practical applications.

[0032] Furthermore, the lubricant includes one or more of pentaerythritol stearate, silicone, and polyethylene wax. These types of lubricants can form better synergistic effects with other components, reduce the viscosity of the polymer melt, and improve its fluidity; at the same time, they reduce friction between the polymer melt and the processing equipment, prevent adhesion, reduce processing energy consumption, and reduce equipment wear.

[0033] Furthermore, the high-performance polyester composite material satisfies at least one of the following characteristics (1)-(7): (1) The flow length ratio of the high-performance polyester composite material is ≥600mm; (2) The tensile strength of the high-performance polyester composite material is 117-136 MPa; (3) The flexural strength of the high-performance polyester composite material is 190-215 MPa; (4) The notched impact strength of the high-performance polyester composite material is 8.3-9.5 KJ / m²; (5) The high-performance polyester composite material can achieve the UL94 V-0 flame retardant rating when the thickness is 0.4 mm; (6) The degree of fiber floating on the surface of the high-performance polyester composite material is slight; (7) The warpage of the high-performance polyester composite material is 60-75%.

[0034] The high-performance polyester composite material of this invention uses butylene terephthalate of a specific viscosity, employs a hydroxyl-containing hyperbranched polymer as a flow aid, and combines alkali-free short glass fibers with ground glass fibers. Simultaneously, the amount of each raw material is limited within a reasonable range to achieve better synergistic effects among the components, thus achieving a balance of high flowability, low fiber float, low warpage, and high strength. Experiments have demonstrated that the high-performance polyester composite material of this invention, while maintaining flame retardancy (0.4 mm UL94 V-0) and mechanical properties (tensile strength 117-136 MPa, flexural strength 190-215 MPa, notched impact strength 8.3-9.5 kJ / m²), achieves ultra-high flowability (flow length ratio 600-710 mm), excellent surface quality (slight fiber float), and low warpage performance, meeting the stringent molding requirements of automotive electronics and ultra-thin precision parts.

[0035] According to a second aspect of the present invention, the present invention also provides a method for preparing the above-described high-performance polyester composite material, comprising the following steps: Step (1): Premix polybutylene terephthalate, toughening agent, antioxidant, lubricant, flow aid, and ground glass fiber to obtain a mixture; Step (2): The obtained mixture is melt-blended with alkali-free short glass fiber, brominated flame retardant and flame retardant synergist, and then extruded and granulated.

[0036] The preparation method of the high-performance polyester composite material of the present invention includes premixing and melt blending steps. During premixing, some additives (toughening agents, antioxidants, lubricants, flow aids, and ground glass fibers) are premixed with polybutylene terephthalate (PBT) to ensure the initial uniform dispersion of these small molecules or short fibers in the PBT matrix, laying the foundation for subsequent melt blending. The melt blending process further ensures that all components, including alkali-free short glass fibers, brominated flame retardants, and flame retardant synergists, are fully mixed and uniformly dispersed in the PBT matrix, avoiding component agglomeration and thus ensuring the uniformity and consistency of the final granules and products.

[0037] In this invention, the extruder used for melt blending in step (2) may include multiple heating zones, for example, between eight and thirteen, depending on the process requirements. The temperature of each heating zone can be adapted to the properties of the material and the function of each heating zone.

[0038] Furthermore, the extruder used for melt blending in step (2) includes ten heating zones, where the temperature of zone one is 210~230℃, the temperature of zones two to six is ​​220~230℃, the temperature of zones seven and eight is 240~250℃, and the temperature of zones nine and ten is 230~240℃; the residence time of the material in the extruder is 25-60s.

[0039] The above scheme has carefully designed the temperature distribution scheme of the extruder and controlled the residence time of the entire material in the extruder to 25-60s, thereby optimizing the melt blending process of polybutylene terephthalate (PBT) composite material. This ensures the smooth progress of the entire process from solid feeding to complete melting, uniform mixing, and stable extrusion, ultimately producing high-performance polyester composite material particles with highly consistent performance and stable quality.

[0040] In this invention, the temperature of zone 1 is 210~230℃, for example, it can be 210℃, 215℃, 220℃, 225℃ or 230℃, as well as specific point values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0041] In this invention, the temperature of zones two to six is ​​220~230℃, for example, it can be 220℃, 221℃, 222℃, 223℃, 224℃, 225℃, 226℃, 227℃, 228℃, 229℃ or 230℃, as well as specific point values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0042] In this invention, the temperature of zones seven and eight is 240~250℃, for example, it can be 240℃, 241℃, 242℃, 243℃, 244℃, 245℃, 246℃, 247℃, 248℃, 249℃ or 250℃, as well as specific point values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0043] In this invention, the temperature of zones nine and ten is 230~240℃, for example, it can be 230℃, 231℃, 232℃, 233℃, 234℃, 235℃, 236℃, 237℃, 238℃, 239℃ or 240℃, as well as specific point values ​​between the above points. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific point values ​​included in the range.

[0044] Preferably, in step (2), the mixture obtained is fed from the main feed port of zone one, the bromine flame retardant and flame retardant synergist are fed from the side feed port of zone four, and the alkali-free short glass fiber is fed from the side feed port of zone seven.

[0045] The above solution achieves precise control over the material processing process by optimizing the feeding positions of different components in the extruder, thereby maximizing the reinforcing effect (by protecting the glass fiber length), optimizing the flame retardant properties (by protecting the activity of the flame retardant), ensuring the uniformity of matrix plasticization, and ultimately producing high-performance polyester composite materials with excellent and stable properties.

[0046] In the preparation method of this invention, the heat transferred to the material by the extruder barrel itself is actually very small. The heat is mainly generated by the shear friction between the materials, allowing them to melt and mix more quickly and uniformly. During the entire extrusion process, the temperature set by the extruder has little impact on the overall performance of the material. However, differences in the production process have a significant impact on the mechanical properties, flowability, and color of the extruded product. Most companies in the industry focus on the torque and current of the extruder during twin-screw extrusion production. However, torque and current do not represent the actual energy input to the material. The heating state of the material and the absorption of heat energy during twin-screw extrusion are affected by multiple factors. The energy in the system is ultimately absorbed by the material, and this energy significantly affects the dispersion and degradation behavior of the material. This has a significant impact on the overall mechanical properties and flowability of the extruded material. Therefore, the energy input to the material is a very important processing parameter.

[0047] Preferably, the unit specific energy consumption of extrusion granulation is 0.17-0.2 kWh / kg.

[0048] Specific energy consumption per unit represents the total energy input into a unit mass of material in the extrusion system. It is closely related to the mechanical properties and flowability of the product. Furthermore, by using specific energy consumption as the core of the process adjustment, the stability of the material during extrusion production can be better improved.

[0049] The formula for calculating specific energy consumption per unit is SME = [(maximum power of equipment / maximum screw speed) * actual screw speed * (actual torque percentage / 100)] / total feed rate. Here, the units of maximum screw speed and actual screw speed are rpm, and the unit of total feed rate is kg / h. The specific energy consumption per unit of material in a twin-screw extruder is calculated by the relationship between the maximum power and maximum speed of the extrusion equipment and the actual set production speed, output, and real-time torque.

[0050] By limiting the unit specific energy consumption, it helps to reduce the aggregation and shear degradation of materials during the extrusion process, thereby keeping the dispersion and degradation of materials in the extruder in a relatively balanced and stable state. Under this balanced state, the mechanical properties can still be maintained at a high level, while the flowability of the material will be improved to a certain extent.

[0051] The extruder can be a conventional extruder, such as the Coperion 58 extruder.

[0052] According to a third aspect of the present invention, the present invention also provides the application of the above-described high-performance polyester composite material or the high-performance polyester composite material prepared by the above-described preparation method in automobiles or electronic appliances.

[0053] The beneficial effects of this invention are: This invention provides a high-performance polyester composite material using polybutylene terephthalate of a specific viscosity, employing a hydroxyl-containing hyperbranched polymer as a flow aid, and combining alkali-free short glass fibers with ground glass fibers. Simultaneously, the amount of each raw material is limited within a reasonable range, allowing for better synergistic effects among the components. This results in a composite material that combines high flowability, low fiber float, low warpage, and high strength. Furthermore, through process design with low energy consumption per unit area, the flowability and production stability of the polyester composite material are further improved.

[0054] The high-performance polyester composite material of the present invention has a flow length ratio of over 600 mm and maintains high notched impact strength, making it suitable for use in the automotive and electronics industries, and especially promising for applications in complex and thin-walled products. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0056] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0057] PBT Resin A: Nantong Xingchen 1084 resin was selected, with an intrinsic viscosity of 0.86 dl / g; PBT resin B: Nantong Xingchen 1100HQ resin was selected, with an intrinsic viscosity of 0.97 dl / g; PBT resin C: Nantong Xingchen 1110 resin was selected, with an intrinsic viscosity of 1.1 dl / g; Antioxidant A: RIANOX1010 is selected; Antioxidant B: RIANOX412S was selected; Bromine-based flame retardant: Israel Chemicals polypentabromobenzyl acrylate FR1025 was selected; Flame retardant synergist: Antimony trioxide (998 concentration), commercially available; Toughening agent: PTW, DuPont, USA; Alkali-free short glass fiber: Alkali-free glass fiber from China Glass Fiber Jushi Group, with a diameter of 11μm and a length of 4.5mm; Ground glass fiber A: Chongqing International, bulk density: 0.5-0.6 kg / l; diameter 9-14 μm, average fiber length 100 μm; Ground glass fiber B: Chongqing International, bulk density: 0.25-0.4 kg / l; diameter 9-14 μm, average fiber length 300 μm; Ground glass fiber C: Chongqing International, bulk density: 0.65-0.75 kg / l; diameter 9-14 μm, average fiber length 50 μm; Lubricant: Pentaerythritol stearate PETS, commercially available; Black masterbatch: Cabot Corporation, UN2014; Flow aid: Hydroxyl-containing hyperbranched polyester, Boltorn H20, hydroxyl value 510 mg KOH / g, Perstorp.

[0058] The extruder used in the following examples and comparative examples is a Coperion 58 extruder with a maximum power of 355KW and a maximum speed of 900RPM.

[0059] Example 1 This embodiment provides a high-performance polyester composite material, the components of which, by weight, are as follows: The formula comprises: 50 parts polybutylene terephthalate (PBT resin) A, 22 parts alkali-free short glass fiber, 8 parts ground glass fiber A, 3 parts toughening agent, 0.3 parts antioxidant A, 0.3 parts antioxidant B, 0.5 parts lubricant, 10 parts brominated flame retardant, 5 parts antimony trioxide flame retardant synergist, 0.3 parts flow aid, and 0.6 parts black masterbatch. See Table 1 for the formulation.

[0060] This embodiment also provides a method for preparing the high-performance polyester composite material, including the following steps: (1) Weigh each raw material according to the ratio, and premix the polybutylene terephthalate, toughening agent, antioxidant, lubricant, flow aid and ground glass fiber to obtain a mixture.

[0061] (2) The mixture obtained in step (1) is fed into an extruder with alkali-free short glass fiber, bromine flame retardant and flame retardant synergist for melt blending. The unit specific energy consumption is controlled at 0.17-0.20 kWh / kg for extrusion granulation to obtain the final product.

[0062] The extruder described in step (2) includes ten heating zones, with the temperature of zone one being 210°C, zone two being 220°C, zones three to six being 230°C, zones seven and eight being 240°C, zones nine and ten being 230°C, the die head being 230°C, and the material residence time in the extruder being 30s.

[0063] In step (2), the mixture obtained in step (1) is fed into the main feed port of zone one, the bromine flame retardant and flame retardant synergist are fed into the side feed port of zone four, and the alkali-free glass short fiber is fed into the side feed port of zone seven.

[0064] Example 2 This embodiment provides a high-performance polyester composite material, the composition of which is shown in Table 1 below. The only difference from Embodiment 1 is that PBT resin B is used instead of PBT resin A.

[0065] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0066] Example 3 This embodiment provides a high-performance polyester composite material, the composition of which is shown in Table 1 below. The only difference from Example 1 is that the amount of PBT resin A is 50.2 parts and the amount of flow aid is 0.1 parts.

[0067] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0068] Example 4 This embodiment provides a high-performance polyester composite material, the composition of which is shown in Table 1 below. The only difference from Embodiment 1 is that the amount of alkali-free short glass fiber is 20 parts, the amount of ground glass fiber A is 10 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 2:1.

[0069] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0070] Example 5 This embodiment provides a high-performance polyester composite material, the composition of which is shown in Table 1 below. The only difference from Embodiment 1 is that: the amount of PBT resin A is 55 parts, the amount of bromine flame retardant is 10 parts, the amount of alkali-free short glass fiber is 20 parts, the amount of ground glass fiber A is 5 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 4:1.

[0071] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0072] Example 6 This embodiment provides a high-performance polyester composite material, the composition of which is shown in Table 1 below. The only difference from Embodiment 1 is that the amount of alkali-free short glass fiber is 15 parts, the amount of ground glass fiber A is 15 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 1:1.

[0073] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0074] Example 7 This embodiment provides a high-performance polyester composite material, the composition of which is shown in Table 1 below. The only difference from Example 1 is that the amount of PBT resin A is 49.8 parts and the amount of flow aid is 0.5 parts.

[0075] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0076] Example 8 This embodiment provides a high-performance polyester composite material, which differs from Embodiment 1 only in that: the amount of PBT resin B is 45 parts, the amount of alkali-free short glass fiber is 27 parts, the amount of ground glass fiber A is 8 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 3.375:1.

[0077] The preparation method of the high-performance polyester composite material in this embodiment is the same as that in Example 1.

[0078] Example 9 This embodiment provides a high-performance polyester composite material, which differs from Embodiment 1 only in that: the amount of PBT resin A is 59 parts, the amount of bromine flame retardant is 11 parts, the amount of alkali-free short glass fiber is 15 parts, the amount of ground glass fiber A is 5 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 3:1.

[0079] Comparative Example 1 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that the amount of flow aid is 0.05 parts and the amount of PBT resin A is 50.25 parts.

[0080] Comparative Example 2 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that the amount of flow aid is 0.7 parts and the amount of PBT resin A is 49.6 parts.

[0081] Comparative Example 3 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that the amount of flow aid is 1 part and the amount of PBT resin A is 49.3 parts.

[0082] Comparative Example 4 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that PBT resin C is used instead of PBT resin A.

[0083] Comparative Example 5 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below and is the same as that of Example 1. The difference in its preparation method compared to Example 1 is that the specific energy consumption is controlled at 0.14-0.16 kWh / kg.

[0084] Comparative Example 6 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below and is the same as that of Example 1. The difference in its preparation method compared to Example 1 is that the specific energy consumption is controlled at 0.21-0.23 kWh / kg.

[0085] Comparative Example 7 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that ground glass fiber B is used instead of ground glass fiber A. The preparation method is the same as in Example 1.

[0086] Comparative Example 8 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that ground glass fiber C is used instead of ground glass fiber A. The preparation method is the same as in Example 1.

[0087] Comparative Example 9 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that the amount of alkali-free short glass fiber is 26 parts, the amount of ground glass fiber A is 4 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 6.5:1. The preparation method is the same as in Example 1.

[0088] Comparative Example 10 This comparative example provides a high-performance polyester composite material, the composition of which is shown in Table 2 below. The only difference from Example 1 is that the amount of alkali-free short glass fiber is 10 parts, the amount of ground glass fiber A is 25 parts, and the weight ratio of alkali-free short glass fiber to ground glass fiber A is 0.4:1. The preparation method is the same as in Example 1.

[0089] Table 1

[0090] Table 2

[0091] The compositions prepared in Tables 1 and 2 above were subjected to the following performance tests: Tensile properties were assessed by tensile breaking strength, measured according to ASTM D638 standard, with sample size of 165mm × 13mm × 3.2mm, test speed of 10mm / min, and testing equipment was a German Zwick universal testing machine.

[0092] Bending strength was measured according to ASTM D790 standard. The sample size was 127mm × 12.7mm × 3.2mm, the test speed was 10mm / min, the span was 50mm, and the test equipment was a German Zwick universal testing machine.

[0093] The IZOD notched punch was tested according to ASTM D256 standard. The sample size was 64mm × 12.7mm × 3.2mm, the notch depth was 2.5mm, and the testing equipment was a German Zwick impact tester.

[0094] The flow length ratio is the ability of a material melt to fill a mold cavity under certain temperature and pressure. The sample has a coil-like structure with a thickness of 2mm. The injection temperatures are 220℃ for section 1, 250℃ for section 2, and 255℃ for sections 3-5. The injection speeds are 50mm / s for sections 1-2, 60mm / s for section 3, and 100mm / s for section 4. The injection pressure is 1500kgf / cm². 2 The injection molding equipment is from Sumitomo, Japan.

[0095] Warpage was measured by injection molding 60*60*1mm samples under the same conditions, stacking samples at the same location, with a stack size of 10, and measuring the highest height of the stacked samples. Warpage was calculated using the following formula: Warpage % = [(maximum height of ten stacked pieces - 10mm) / 10mm] * 100%.

[0096] For the appearance of fiber floating, 60*60*3mm samples were injection molded under the same conditions. The surface of the samples was compared visually and under 150x magnification with an optical microscope. The severity of whitening due to fiber floating was observed under microscope magnification. The severity of fiber floating was judged as follows: severe > moderate > slight.

[0097] Table 3 Performance Comparison Table of Examples 1-9

[0098] Table 4 Performance Comparison Table for Comparative Examples 1-10

[0099] As can be seen from the experimental data in Table 3, when the specific energy consumption (SME) is precisely controlled within 0.17-0.20 kWh / kg (Examples 1-9), and a specific viscosity PBT, flow aid, and alkali-free short glass fiber / ground glass fiber composite system are used in combination, the flowability of the polyester composite material can be improved, resulting in a flow length ratio ≥600 mm. Extending the molding cycle also improves the flow length ratio. The polyester composite material of this invention also possesses high strength, low fiber float, and low warpage properties, with a tensile strength of 117-136 MPa, a flexural strength of 190-215 MPa, and a notched impact strength of 8.3-9.5 kJ / m. 2 The floating fibers are only "slight," with a warpage of 61-74%.

[0100] As can be seen from the experimental results of Example 1 and Comparative Examples 1, 2, and 3 in Tables 3 and 4, hydroxyl-containing hyperbranched polyester can improve the flowability of the material. However, when the addition ratio is too high, although it can increase the flow length ratio, the vigorous reaction of the hyperbranched structure produces a large number of cross-linked structures, which prolongs the molding cycle and actually reduces the flow length ratio, severely impairing the mechanical properties of the material. Tensile strength, flexural strength, and notched impact strength are significantly reduced. When the addition ratio is too low, the improvement in flow length ratio is not significant, and the appearance of loose fibers is more pronounced, and the warpage is increased. Only by limiting the amount of hydroxyl-containing hyperbranched polyester within the precise range shown in Example 1 can the comprehensive performance of the material be synergistically achieved.

[0101] As can be seen from Examples 1 and Comparative Example 4 in Tables 3 and 4, the viscosity of PBT resin is too high and the molecular chains of the matrix material are tightly wrapped. Even with the synergistic effect of using hydroxyl-containing hyperbranched polyester, alkali-free short glass fiber and ground glass fiber, the flowability improvement is limited and the flow length ratio of more than 600 mm is not achieved, and the fiber floating is serious.

[0102] Furthermore, the comparison results of Example 1 and Comparative Example 5 in Tables 3 and 4 show that the unit energy consumption of processing is too low, the material flow length ratio is significantly low, and the fiber floating is serious. The comparison results of Example 1 and Comparative Example 6 show that the unit energy consumption of processing is too high, the material flow length ratio is significantly improved, but the material degrades too much during processing, resulting in a significant decrease in overall mechanical strength.

[0103] As can be seen from Examples 1 and Comparative Examples 7 and 8 in Tables 3 and 4, the bulk density of ground glass fiber affects the flowability and mechanical properties of the material. Low bulk density results in good performance but insufficient improvement in flowability. High bulk density can significantly improve flowability but significantly reduce notched impact strength.

[0104] As shown in Tables 3 and 4 for Examples 1 and Comparative Examples 9 and 10, using alkali-free short glass fibers and ground glass fibers in a ratio of (1-4):1 can improve the flow length ratio of the material and also provide high strength, low fiber float, and low warpage. When the ratio of alkali-free short glass fibers to ground glass fibers is too low, although it improves the flowability of the material, the mechanical strength of the material is significantly reduced. When the ratio of alkali-free short glass fibers to ground glass fibers is too high, the improvement in flowability is not significant, and fiber float is severe with high warpage.

[0105] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high performance polyester composite material, characterized in that, According to the weight parts, comprising the following components: Polybutylene terephthalate 35~60 parts Bromine flame retardant 10~20 parts Flame retardant synergist 2~6 parts Toughening agent 1~5 parts Glass fiber 10~40 parts Antioxidant 0.1~1 parts Lubricant 0.1~2 parts Flow aid 0.1~0.6 parts; The intrinsic viscosity of the polybutylene terephthalate is 0.75-1.0 dl / g; the glass fiber includes alkali-free short glass fiber and ground glass fiber; the flow aid is a hydroxyl-containing hyperbranched polymer.

2. The high performance polyester composite of claim 1, wherein, The hydroxyl-containing hyperbranched polymer is one or more of hydroxyl-containing hyperbranched polyester and hydroxyl-containing hyperbranched polyamide ester; Preferably, the mass percentage of the flow aid in the amount of the high-performance polyester composite is 0.1-0.5%; Preferably, the hydroxyl value of the hydroxyl-containing hyperbranched polymer is 300-550 mgKOH / g.

3. The high performance polyester composite of claim 1, wherein, The weight ratio of the alkali-free short glass fiber to the ground glass fiber is (1-4):1; Preferably, the fiber diameter of the alkali-free short glass fiber is 10-13 μm, and the length is 3-5 mm; the bulk density of the ground glass fiber is 0.5-0.6 kg / L, the fiber diameter is 9-14 μm, and the average length is 80-200 μm, preferably 80-150 μm.

4. The high performance polyester composite of claim 1, wherein, The intrinsic viscosity of the polybutylene terephthalate is 0.8-0.95 dl / g.

5. The high performance polyester composite according to any one of claims 1 to 4, characterized in that, According to the weight parts, comprising the following components: Polybutylene terephthalate 45~59 parts Bromine flame retardant 10~15 parts Flame retardant synergist 2~6 parts Toughening agent 1~5 parts Glass fiber 20~35 parts Antioxidant 0.1~1 parts Lubricant 0.1~2 parts Flow aid 0.1~0.5 parts.

6. The high performance polyester composite of claim 1, wherein, The bromine flame retardant is one or more of brominated epoxy resin, brominated polystyrene, decabromodiphenyl ethane, poly (pentabromobenzyl acrylate), brominated imine, brominated polycarbonate and brominated triazine; preferably, the bromine flame retardant is one or more of brominated epoxy resin, brominated polystyrene and poly (pentabromobenzyl acrylate); And / or, the flame retardant synergist is antimony trioxide or sodium antimonate; And / or, the antioxidant is one or more of hindered phenolic, phosphite and thioester antioxidants; And / or, the toughening agent is one or more of ethylene-methyl acrylate-glycidyl methacrylate, ethylene-butyl acrylate-glycidyl methacrylate, ethylene-butyl acrylate and ethylene-vinyl acetate copolymer; The lubricant includes one or more of pentaerythritol stearate, silicone and polyethylene wax.

7. The high performance polyester composite according to any one of claims 1 to 6, characterized in that, The high-performance polyester composite satisfies at least one of the following characteristics (1)-(7): (1) The flow length ratio of the high-performance polyester composite is ≥600 mm; (2) The tensile strength of the high-performance polyester composite is 117-136 Mpa; (3) The bending strength of the high-performance polyester composite is 190-215 Mpa; (4) The notched impact strength of the high-performance polyester composite is 8.3-9.5 KJ / m²; (5) the high-performance polyester composite material can reach UL94 V-0 flame retardant grade under the condition of 0.4mm thickness; (6) the high-performance polyester composite material has slight floating fiber degree in appearance; (7) the high-performance polyester composite material has a warpage degree of 60-75%.

8. Process for the production of high performance polyester composites according to any one of claims 1 to 7, characterized in that, The method comprises the following steps: Step (1): premixing polybutylene terephthalate, toughening agent, antioxidant, lubricant, flow aid and ground glass fiber to obtain a mixture; Step (2): melt blending the obtained mixture with alkali-free short glass fiber, bromine-based flame retardant and flame retardant synergist, and extruding and granulating.

9. The production method according to claim 8, characterized by, The extruder used for melt blending in the step (2) comprises ten heating zones, wherein the temperature of the first zone is 210-230℃, the temperature of the second zone to the sixth zone is 220-230℃, the temperature of the seventh zone and the eighth zone is 240-250℃, and the temperature of the ninth zone and the tenth zone is 230-240℃; the residence time of the material in the extruder is 25-60s; Preferably, in the step (2), the obtained mixture is fed from the first zone main feeding port, the bromine-based flame retardant and the flame retardant synergist are fed from the fourth zone side feeding port, and the alkali-free short glass fiber is fed from the seventh zone side feeding port; Preferably, the unit specific energy consumption of the extruding and granulating is 0.17-0.2kWh / kg.

10. Application of the high-performance polyester composite material according to any one of claims 1-7 or the high-performance polyester composite material prepared by the preparation method according to claim 8 or 9 in automobiles or electronic appliances.

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